Canon POWERSHOT SD750 DIGITAL ELPH User Manual page 50

It may be difficult to focus on the following types of subjects.
oSubjects with extremely low contrast to the surroundings
oScenes with a mixture of near and far subjects.
oSubjects with extremely bright objects at the center of the composition
oSubjects that are moving quickly
oSubjects through glass: Try to shoot as close to the glass as
possible to reduce the chances of light reflecting back off the glass.
Shooting with the Focus Lock
The focus lock can be used in any shooting mode.
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Shooting with the AF Lock
The AF lock can be used in the [_, L'_, I_-], _, _1_or I_ mode.
Aim the camera so that an object at the
same focal distance as the main subject
centered in the AF frame.
is
Re-aim the camera to compose the shot as
desired and shoot.
Press the shutter button halfway and press
the _/,A button.
eThe _ icon will display.